Is web browser JavaScript runtime?

Question

In Node.js website, they say Node.js is a JavaScript runtime.

Are web browsers like Chrome, Firefox, Edge, ... JavaScript runtimes?

I thought of course, web browser is JS runtime. But I'm confused, In this video 12:10~ He says Web browser is not just JavaScript runtime because it can do more things at one time, it can give us other things.

But I think V8 engine only can do one thing at one time, while JS runtime can do more things than one at one time.

Am I wrong?

Answer 1

A browser contains a Javascript engine (for example Chrome v8). The engine implements a Javascript runtime, which includes the call stack, heap and event loop. The browser also usually includes a set of APIs that augment the Javascript runtime and make asynchronous code execution possible. NodeJS also implements a Javascript runtime using Chrome's v8 engine as well as the Libuv library (event loop and worker threads).

Here's a good video that breaks this all down: https://www.youtube.com/watch?v=4xsvn6VUTwQ

Answer 2

They are right, a JavaScript runtime just executes the JavaScript code.

All Web browsers include a JavaScript runtime engine(RE) that executes js code for them but they also have other plugins like java or flash, as well as an html/dom parser and renderers that are not part of the RE, even if those modules were written in JavaScript it does not mean they would be part of the RE.